Bore hole plug

ABSTRACT

There is provided a new and useful bore hole plug comprising a central support member, an expandable sleeve secured about the central support, a first reactant chemical within the sleeve which is capable of reacting with a second reactant chemical or a catalyst to form a closed cell foam, and means by which the second reactant can be introduced to the sleeve.

This application relates to bore hole plugs.

BACKGROUND OF THE INVENTION

In carrying out a seismic exploration, a standard procedure is to drillholes into the geologic formations of interest and to plant explosivecharges in the bore holes. The charges are then detonated andappropriate measurements recorded to enable evaluation of the formation.

There are a number of problems associated with this seismic drilling.One of these occurs during the actual blast. Unless the hole is properlyplugged prior to detonation, a large proportion of the energy of theblast escapes upwardly through the hole and is thus not properlydirected through the formation of interest.

A second problem which frequently arises is that the boring and blastreleases from the formation water under pressure which then escapesthrough the hole. A bore hole plug is necessary to stop the water flow.

There is therefore a continuing need for a bore hole plug which issimple and inexpensive in construction yet sufficiently durable toremain in place for extended periods and to withstand the force of theblast and of the water. To date, a variety of plugs have been proposedand used, but these do not satisfactorily meet all of the criteria setout above.

The bore hole plug of the present invention is intended to alleviate theproblems discussed.

PRIOR ART

There are a number of United States and Canadian patents which fall intothe general area of interest but which are deficient in one or otheraspects. Among United States patents of interest is U.S. Pat. No.2,609,880, issued Sept. 9, 1952 to one Dyer. In this case the containeris partitioned to contain two reactants such as water and cement. Theobject, however, is to plug a fracture or the like at the side of thebore hole, and the device would not be suitable nor is it intended toseal the bore hole itself. In particular, the container is destroyed orremoved from the hole in bringing the two reactants together, and it istherefore not apparent that any seal at all would be formed in the borehole itself.

U.S. Pat. No. 2,966,946, issued Jan. 3, 1961, to McCulloch et al.,provides a rather complex device one aspect of which is an airinflatable sleeve. Compressed air is provided from a cylinder that isheld within the plug. Inherent in this device are the disadvantages ofall of the air inflated types; namely, that there is a tendency over thelong term for leakage and deflation and, as well, there is a real dangerof rupture. Clearly, rupture of the sleeve is disastrous in an airinflated device.

U.S. Pat. No. 3,130,787, issued Apr. 28, 1960 to Mason, is a relativelysimple inflatable bag type plug. In addition to the disadvantagesgenerally inherent in air inflatables, this device has in addition thedisadvantage that it is inflated via compressor and piping from thesurface and therefore adds this complexity and expense.

Canadian Pat. No. 703,786, issued Feb. 16, 1965, to Smith providesanother air expandable plug. This device has a number of disadvantagessimilar to those of the Mason patent.

Canadian Pat. Nos. 840,218, issued Apr. 28, 1970 and 889,694 issued Jan.4, 1972, both to Bassani, provide yet another air inflatable where theair for inflation is provided from the surface.

Canadian Pat. Nos. 921,399, issued Feb. 20, 1973 and 951,241, issuedJuly 16, 1974 both to Schlumburger Canada Limited, are typical of alarge group of prior art patents which pertain to complex plugarrangements, designed with a flow through bridge which can eventuallybe blocked to provide a complete plug. In general the complexity ofthese devices adds greatly to the expense and renders them undesirablefor use in seismic drilling.

Finally, Canadian Pat. No. 1,117,865, issued Feb. 9, 1982, to Ditto,provides another air inflated plug wherein the gas cylinder providingthe compressed air is located in the plug. The air release is by way ofan electrically operated valve which is in turn connected to the surfaceand to a source of electric current by a pair of lead wires. Again, thisdevice has the disadvantage of the air inflatables with surfaceconnection.

In contrast, the plug of the present invention utilizes an inflatablesleeve and reactants which are brought into contact to form an expandingsettable foam which sets in the bore hole to form an effective anduniform seal. The effectiveness of the seal is thus not affected byleakage nor by rupture of the sleeve.

SUMMARY OF THE INVENTION

The invention utilizes an inflatable bag or sleeve to effect a uniformand permanent plug in a bore hole. At least one source of reactant islocated within the sleeve and means is provided for effecting contactbetween the first reactant and a second reactant or a catalyst, thesource of which may or may not be located within the sleeve. Thereactants are chosen such that, upon contact, they react to expand intoa settable foam. The foam sets in the hole to form an extremely hard anddurable plug.

Accordingly, the invention provides a bore hole plug comprising acentral support member, an expandable sleeve secured about the centralsupport, a first reactant chemical within said sleeve which is capableof reacting with a second reactant chemical to form a closed cell foam;and means by which the second reactant can be introduced to the sleeve.

In a further embodiment the invention provides a bore hole plugcomprising a central support member, an expandable sleeve secured aboutthe central support, at least two discrete sources of reactant chemicalswithin the sleeve, each of which provides a chemical, the chemicalsbeing such that they react upon contact with each other to expand into asettable foam, and means associated with the central support member foreffecting contact between the reactants.

In a further embodiment the invention provides a bore hole plugcomprising a central hollow cylindrical support member having a pair ofslots through the side wall thereof and having top and bottom endclosures, an expandable sleeve member secured about the support memberand encompassing the slots, a pair of fracturable containers within thesleeve and disposed adjacent the slots, each containing a reactantchemical, the chemicals chosen such that they react upon contact witheach other to expand into a settable foam, a pair of arms pivotallymounted in the central member and adapted to rotate from a firstposition within the member to a second position extending throughrespective ones of the slots, and a control rod extending through andslidable relative to the top closure for effecting rotation of the arms,whereby rotation of the arms from the first to the second positioncauses the arms to fracture the containers to thereby effect contactbetween the reactants.

BRIEF DESCRIPTION OF THE DRAWINGS

In drawings which illustrate embodiments of the invention,

FIG. 1 is a side elevation partly in section of a plug according to theinvention;

FIG. 2 is a side elevation partly in section illustrating a furtherembodiment of the invention;

FIG. 3 is a view similar to FIG. 2 where the plug has been inflated;

FIG. 4 is a side elevation partly in section illustrating a furtherembodiment of the invention.

While the invention will be described in conjunction with theillustrated embodiments, it will be understood that it is not intendedto limit the invention to such embodiments. On the contrary, it isintended to cover all alternatives, modifications and equivalents as maybe included within the spirit and scope of the invention as defined bythe appended claims.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, similar features in the drawings have beengiven similar reference numerals.

With reference to FIG. 1, plug 10 comprises the central support member12 about which is secured the inflatable sleeve 14. Sleeve 14 is securedby means of clamp 16 to the lower end cap or collar 18 and by means ofclamp 20 to the upper end collar 22. End cap 18 and collar 22 aresecured to the central support member 12. End cap 18 is preferablycone-shaped at the lower end to facilitate entry and travel of the plugin the bore hole.

The member 12 is preferably a length of PVC plastic pipe, and the endcap 18 and the collar 22 are preferably of ABS plastic. Typically theplug will have an overall length in the area of eighteen inches. Thediameter of uninflated sleeve 14 and of end cap 18 and collar 22 aresuch as to provide sufficient clearance for insertion of the plug into abore hole.

The sleeve 14 is an expandable elastic material such as rubber.

The member 12 is provided with at least one opening for communicationbetween the interior 24 of the member 12 and the interior 26 of thesleeve 14. In FIG. 1 four such openings comprising elongated slots 28are illustrated.

Also in FIG. 1 the tubular member 12 is provided with a closure 30comprising, as illustrated, a threaded plug. In the case illustrated theplug is actually inserted into a tube 31 leading to tube 12. However,plug 30 could as well be attached directly to collar 22. Any similarremoveable closure 30 to seal the member 12 would be suitable and, inparticular, once in place in a use situation, it is not contemplatedthat the closure 30 would normally be removed. Therefore, it isgenerally only necessary that the closure 30 seal and hold adequatelyagainst the expanding foam, so a quick setting cement, a clamp, or thelike may be found suitable in some situations.

The plug 10 includes, in the most general configuration, illustrated inFIG. 1, a first chemical reactant 32 located in the sleeve 14. Thisreactant is one which, upon contact with a second reactant or a catalyst33, reacts and expands to form a closed cell foam.

In use the closure 30 is removed, the catalyst 33 added to the tubularmember 12, and the closure 30 replaced. The whole container is thenagitated, as by hand shaking, to promote movement of the first reactantand the catalyst between the tubular member 12 and the sleeve 14 topromote good contact. The plug is then simply dropped into the bore holewhere the reaction goes to completion, expanding the sleeve 14 tightlyagainst the bore hole walls to effect the seal.

Clearly, in seismic blasting, the explosive charge will have been set inthe bore hole prior to insertion of the plug.

In the flow control case, it may be necessary to hold the plug at theproper depth in the hole until the foam has set. This can be done byutilizing rods extending from the surface down into the borehole tothreadedly engage the end collar 22 in place of plug 30. The rods canthen be removed when the foam has set.

In a modification of this embodiment, the catalyst or second reactant 33may be located in a fracturable container in the tube 12. Prior to usethe plug 30 is removed and a suitable prod inserted to tear or break thefracturable container. The prod is then removed, plug 30 reinserted, andthe plug 10 shaken. The plug 10 is then inserted into the hole prior tothe foam setting. As with the first embodiment discussed above, in thecase of a flowing hole, the closure 30 can be replaced by a connectionto the surface to position the plug 10 until setting is complete.

A second embodiment of the invention is illustrated in FIG. 2. In thatembodiment the plug as an operating unit is completely self-contained inthat both the first and second reactants are located within the sleeve14.

Preferably, the reactants are located in a pair of containers 34 and 36in proximity to central member 12. The chemicals as above are chosen toreact upon contact to expand into a settable foam. The foam is chosen tobe of a type that will set into a very hard material.

In order to effect contact between the chemicals in containers 34 and36, the mechanism 37 is provided for breaking or puncturing thecontainers. Clearly, the containers 34 and 36 are comprised of amaterial which can readily be punctured. In the preferred case the meansfor effecting rupture of the containers comprises a plunger arm 38 withwhich is threadedly engaged a set of arms 40 on a pivotting mechanism42. The arms are preferably spring biased toward the closed positionillustrated in FIG. 2.

Prior to use of the plug, the wings 30 are maintained in the closedposition illustrated in FIG. 1 by virture of abuttment against the innerwalls of the member 12 or by the spring bias. To effect rupture of thecontainers 34 and 36 and subsequent contact of the chemicals containedin the containers, the plunger 38 is moved downwardly in the member 12to a position where the wings 40 can extend outwardly through slots 28provided for the purpose in the member 12. A camming mechanism isprovided in the connection 42 to extend the arms 40 when plunger 28 isdepressed. The containers 34 and 36 are preferably positioned adjacentthe slots, so that when the wings 40 move into the open position, thecontainers 34 and 36 will be ruptured and the chemicals will be releasedto contact each other and begin the foaming reaction.

The plunger 38 is removed from the mechanism 42 (by disengaging thethreads) and an end closure such as plug 30 of FIG. 1 is inserted.

The chemicals can be chosen to react at a sufficiently slow rate thatthe plunger can be activeated at the surface to begin the foamingreaction and the plug subsequently dropped into the bore hole. In thissituation, it is unnecessary that there be any connection at all asbetween the plug and the surface of the earth. As with the earliercases, however, a surface connection may be utilized in cases where theplug must be positioned and held until the foam is set in a flowinghole.

The chemicals are chosen to produce a foam which will expandsufficiently to force the sleeve 14 to expand against the walls of thebore hole to form a tight seal. The foam will set to a very hard anddurable mass. Such foams are readily available from manufacturers.

In an alternative embodiment, the wings 40 are spring biased to the openposition of FIG. 3, so that they assume the open position when theplunger 38 is depressed to the point where wings 40 reach the upper endsof slots 28. Continued depression of the plunger with the arms 40extended, further aids in rupture of containers 34 and 36 and insubsequent mixing of the two reactants.

The embodiment illustrated in FIG. 4 enhances the effectiveness of theinvention. While it is applicable to either of the FIGS. 1 or 2embodiments, it is particularly useful with the FIG. 1 situation.

Here the plunger 38 is fitted with a mixing device 44 which may take avariety of forms but is preferably a perforated or webbed ring. The ring44 is joined to the plunger 38 by the rods 46 and 48 which extendthrough the slots 28 in the tubular member 12 to the threaded collar 49.

In operation, and based on the FIG. 1 embodiment, the second reactant orcatalyst would be added to the tubular member 12 and the plunger 38would be moved up and down in the member 12 thereby enhancing mixingbetween the reactants. This may be further enhanced by agitation of theplug as a whole.

The plunger is then preferably removed by unscrewing from threadedcollar 49.

Thus it is apparent that there has been provided in accordance with theinvention a bore hole plug that fully satisfies the objects, aims andadvantages set forth above. While the invention has been described inconjunction with specific embodiments thereof, it is evident that manyalternatives, modifications and variations will be apparent to thoseskilled in the art in light of the foregoing description. Accordingly,it is intended to embrace all such alternatives, modifications andvariations as fall within the spirit and broad scope of the appendedclaims.

What I claim as my invention:
 1. A bore hole plug comprising:a centralsupport member; an expandable sleeve secured about said central support;a first reactant chemical within said sleeve which is capable ofreacting with a second reactant chemical or catalyst to form a closedcell foam; a second reactant chemical or catalyst; and means forenabling said second reactant chemical or catalyst to contact said firstreactant chemical within said sleeve.
 2. The plug of claim 1 wherein thesaid central support member is an elongated tubular member having topand bottom ends and means for closing the bottom end thereof.
 3. Theplug of claim 2 wherein said tubular member is fitted with top andbottom collars to which respective top and bottom members of said sleeveare secured.
 4. The plug of claim 2 wherein said enabling meanscomprises openings in said tubular member for communication between theinterior of said tubular member and the interior of said sleeve.
 5. Theplug of claim 4 including a removeable closure member in the top end ofsaid tubular member.
 6. The plug of claim 5 wherein said closure memberis threadedly attached to said tubular member.
 7. A bore hole plugcomprising:a central support member; an expandable sleeve secured aboutsaid central support; a first reactant chemical within said sleeve whichis capable of reacting with a second reactant chemical or catalyst toform a closed cell foam; and means for enabling a second reactantchemical or catalyst to contact with said first reactant chemical withinsaid sleeve.
 8. A bore hole plug comprising:a tubular central supportmember having a top and bottom end and closed at the bottom end; acollar secured around each end of said member; an expandable sleevehaving top and bottom ends secured respectively to said collars; atleast one opening for communication between the interior of said tubularmember and the sleeve; a removeable closure threadedly secured in thetop of said tubular member; and a first reactant chemical within saidsleeve which is capable of reacting with a second reactant chemical or acatalyst to form a closed cell foam.
 9. The plug of claim 8 wherein saidcentral support member contains a series of elongated slots forcommunication between the interior of said support member and theinterior of said sleeve.